I give up, I need outside help
So a few months ago I got a P0420 code stating my cat is bad. (I could smell it) Now given at this point i have an 06 shinka edition at 114k miles and i e had it since july of last year. I replaced the cat with a turbo xs high flow as well as the matching catback. The code went away since it was the only code that was showing. I also replaced the starter with a series 2, new O2 sensors, and an air filter.
About 24-48 hours later I got a engine misfire in cylinder (rotor) 1. So i replaced my spark plugs. Drove that for about 2 days and another misfire popped up. Had to drive it a few days like that cause its my only working vehicle since my truck took a shit a week after the first upgrades to the mazda. Changed the plug wires and coils (got delphi, BHR wasn't in stock. Tried holding off to get those and couldn't wait.)
Now after all that about a month's worth of troubleshooting my P0420 code is back. My truck isn't fixed yet and toys is my only vehicle. Now as im trying to figure out the cause i noticed when I got home tonight my cat was glowing which it never has before. Is my cat bad again after only having the new one on for only about a month and half? Or is there another underlying issue?